This dissertation project will explore a new methodological approach to understanding the organizational and physician factors which inhibit successful implementation of the collaborative care model for depression. It is known that in order to improve the quality of care for chronic illnesses, both medical groups and individual physicians must enact change: Medical groups must redesign the system of care; physicians must improve their skill and knowledge of care for patients with chronic illnesses. However, the relative importance of the clinic and the individual physicians' role in quality improvement, and the specific factors that inhibit change remain unclear. In this project, a structural model of implementation will be developed which specifies the role of the clinic and the physician in quality improvement. This research will help target the key barriers to implementation and clarify the relative importance of the clinic and the physician in quality improvement. Findings from this study can be used to inform quality improvement initiatives, and to expand the tools available for research on the implementation of evidence-based care. [unreadable] [unreadable]